An apparatus for separating air by cryogenic distillation comprises N air compressors (C1, C2, C3) connected so as to receive air at ambient pressure and designed to produce air at a first pressure above 12 bar absolute, N being at least 3, each of the compressors being driven by a single asynchronous motor (M1, M2, M3), the total power of the compressors being at least 10 MW.

A method and apparatus for separating air in which production of the liquid products can be selectively varied between high and low production rates by varying the pressure ratio across a turboexpander used in imparting refrigeration with the use of a branched flow path. The branched flow path has a system of valves to selectively and gradually introduce a compressed refrigerant air stream into either a booster compressor branch having a booster compressor to increase the pressure ratio during high modes of liquid production or a bypass branch that bypasses the booster compressor to decrease the pressure ratio during low modes of liquid production. A recycle branch is connected to the booster compressor branch to allow compressed air to be independently recycled from the outlet to the inlet of the booster compressor during turndown from the high to the low liquid mode of liquid production to prevent surge.

An air separation plant is provided that includes a plurality of air compressors, a plurality of air purification units, and one or more cold boxes. In a first mode of operation, a first air compressor is configured to compress air to a higher pressure than a second air compressor. In a second mode of operation, the second air compressor is configured to compress air to a higher pressure than during the first mode of operation.

A gas turbine plant includes a gas turbine, a liquefaction facility capable of liquefying air, and a liquefaction controller. A compressor has an intake amount adjuster capable of adjusting an intake amount into a compressor casing. The liquefaction facility includes: a bleed line capable of bleeding compressed air from the compressor; a liquefaction system capable of liquefying the compressed air, a bleed amount adjustment valve; a return air line capable of guiding return air into a flow passage through which compressed air flows in the gas turbine; and a return amount adjusting valve. The liquefaction controller opens the bleed amount adjustment valve if an opening degree of the intake amount adjuster is a first opening degree, and opens the return amount adjusting valve if the opening degree of the intake amount adjuster is a second opening degree, which is an opening degree greater than the first opening degree.

An air separation unit and associated method for separating air by cryogenic distillation using a distillation column system including a higher pressure column, a lower pressure column, an intermediate pressure kettle column, and an argon column arrangement is provided. The present air separation unit and associated method employs a once-through kettle column reboiler, a once-through kettle column condenser, and a once-through argon condenser. The once through argon condenser is disposed within the lower pressure column where an argon-rich vapor stream is condensed against the descending liquid in the lower pressure column.

A system and method for the liquefaction and densification of oxygen for use in space vehicle applications is provided that uses high pressure air or synthetic air as the refrigerant source. The disclosed system and method employs a heat exchanger arrangement comprising a first heat exchange device configured to liquefy the high pressure gaseous oxygen stream and at least a portion of the high pressure gaseous air stream via indirect heat exchange with a refrigerant stream to yield a liquid oxygen stream and a liquid air stream. The heat exchanger arrangement also includes a second heat exchange device configured to densify the liquified oxygen stream via indirect heat exchange with the liquid air stream which yields the densified liquid oxygen and a cold vaporized air stream. The refrigerant stream comprises a mixture of the exhaust streams from one or more turbines with the cold vaporized air stream.

An apparatus and process for argon recovery can be configured so that an argon-enriched stream including oxygen therein can be recycled to a column for air separation and subsequent argon separation to provide improved argon recovery with reduced power. The recycling of this argon-enriched stream can be provided such that there is sufficient nitrogen within the column to facilitate separation of argon from oxygen within the column so additional argon that can be provided via the recycling can be separated and purified instead of being output as a waste stream or otherwise lost.

A process for producing liquid nitrogen utilizes a distillation system comprising higher-pressure and lower-pressure columns, a first condenser in the lower-pressure column bottom, and a second condenser disposed on top of the lower-pressure column. Feed air is compressed in a main air compressor above 15 bar(a) and cooled in a main heat exchanger. A first cooled air portion is expanded in a cold turbine before separation in the higher-pressure column. A second cooled air portion is liquefied before entering the higher-pressure column. Liquid nitrogen streams condensed by both the first and second condensers are combined to yield the final product. Another feature involves warming and expanding a lost air stream (e.g., from the cold turbine outlet and/or higher-pressure column) to below 2 bar(a) in a warm turbine.